Rock drill



J. F. sHooK 1,8025987 A ril 28, 1931.

ROCK DRILL Filed Stept. 18, 1928 1115 Arromvim Patented Apr. 28, 1931 UNITED STATES PATENT OFFICE JAMES F. SHOOK, OF PHILLIPSBURG, JERSEY, ASSIGNOR T0 INGERSOLL-RAND COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY R0 OK DRILL Application filed September 18, 1928. Serial No. 306,629.

This invention relates to rock drills, but more particularly to a fluid actuated rock Y drill of the type in which the piston or pisin part pointed out hereinafter.

In thedrawings accompanying the specification and in which similar reference characters refer to similar parts,

Figure 1 is a sectional elevation of a rock drill constructed in accordance with the practice of the invention and showing the pistons in one of their limiting positions, and

Figure 2 is a view similar to Figure 1 showing the pistons in a reversed position.

Referring to the drawings, A designates generally a rock drill which for the purpose I of illustration may be of a stoper type. The rock drill A comprises an outer cylinder B carrying in this instance at its front end a front head C in which is disposed a chuck D for the reception and guidance of a working implement E, such as a drill steel. The chuck D in this instance has a cavity F in its rearward end into which the working implement extends. In the form illustrated the front head C and the chuck D also serve as closures for the front end of the cylinder B. Preferably the cylinder B is provided with a free exhaust port G for the escape of motive fluid to the atmosphere.

In accordance with the practice of the invention, the rock drill A is provided with an inner cylinder H disposed concentrically within the cylinder B to form an annular piston chamber J between the cylinders. The inner cylinder H has a central chamber K and carries at its rearward end a flange L which overlies the rearward end of the cylinder B and forms a closure for the corre sponding end of the piston chamber J.

In order to centralize the cylinders B and H with respect to each other the flange L is provided with a projection O which extends into and is in body engagement with they cylinder B. The inner cylinder H in this instance is also provided with a free exhaust port or passage P which leads from a point intermediate the ends of the piston chamber K and extends-rearwardly through the cylinder H and the flange L where it opens to the atmosphere.

Disposed within the piston chamber K is a piston Q, shownfor the convenience of illustration as a plugpiston of uniform diameter, and in the piston chamber J is a piston R of annular shape in slidable engagement with the interior surface of the cylinder Band with the exterior surface of the cylinder H.

The pistons Q and R in this instance control the free exhaust ports wherewith the respective piston chambers in which the pistons are disposed are provided.

Means is provided for transmitting the blows of the pistons@ and R to the working implement E. To this end an anvil block 5 is disposed in the front end of the cylinder B and has a projection T at its forward end which extends slidably into the cavity F and is adapted to seat with its forward surface against the end of'the working implement E. The anvil block S is preferably in slidable engagement with the inner surface of the cylinder B in order to form an additional 2- means for preventing leakage of pressure fluid from the front end of the piston chamber J. In the construction shown the anvil block S is provided at its rearward end with a stem U which projects through a bore V in the front end of the cylinder H and into the path of the piston Q. I

A closure is provided for the rearward end of the piston chamber K in the form of a back head WV which in this instance has a projection X extending into the piston chamber K for the purpose of centralizing the back head W with respect to the cylinders. Among other functions the back head W serves as a housing for a throttle valve Y which may be of the rotatable type and accordingly has a throttle lever Z for its manipulation. The throttle valve Y has a central chamber 7) which may be in constant communication with the pressure fluid supply and also has a port 0 which, in the open position of the throttle valve, registers with a passage d in the back head and leading to a supply reservoir 0 also in the back head.

The supply reservoir 6 may be an enlargement of and located intermediate the ends of a transverse bore f formed in the back head In the transverse bore f is disposed a bushing 9 having two annular-rows of ports h and j through which pressure fluid may flow from the supply reservoir 6 into a valve chamber is in the bushing g. The valve chamher is in this instance is formed by a pair of plugs 0 and p disposed in opposite ends of the bushing g and spaced attheir inner ends to form the valve chamber Z0. The plugs 0 and p may be held in operative position in any convenient manner, bolts 9 being 1nd1- cated for this purpose.

The plugs 0 and p are provided with passages o' and s respectively into which pressure fluid may flow from the valve chamber In. From the passage 8 to the rearward end of the piston chamber K leads a reaward inlet passage 13 for conveying pressure fluid into the piston chamber to impel the piston Q, forwardly. A front inlet passage 10 leads from the passage 1" to the front end of the piston chamber'K to convey pressure fluid thereto for impelling the piston Q rearwardly.

In order to insure a simultaneous movement of the pistons Q and R in opposite directions so that one piston will be moving forwardly while the other piston is moving in the opposite direction, a rearward inlet passage '0 is formed in the drill to lead from the passage 1 to the rearward end of the piston chamber J and a passage 10 is formed 1n the drill to lead from the passage 8 to the front end of the piston chamber J. Due to this arrangement of the inlet passages pressure fluid may be. simultaneously admitted to i the rearward end of the piston chamber It and into the front end of the piston chamber J to drive the pistons Q and R in opposite directions with respect to each other, and thus also pressure fluid may be simultaneously admitted into the rearward end of the piston chamber J and into the front end of the piston chamber K. I

Although the means for effecting the distribution of pressure fluid to the piston chambers forms no part of the present invention, the drill however, is shown provided with a distributing valve 00 disposed in the valve chamber to control the admission of pres sure fluid into the passages r and s.

For the sake of simplicity o1 illustration only two pistons are shown. It will, however, be readily apparent that the principle disclosed in the drawings is susceptible of further modification, depending upon the amount of drilling which it is desired to obtain within a given time and other considerations, such as weight and proportions of the drill which the Work for which it is intended will permit. v

The advantages of the present invention will be readily apparent to those skilled in the art. Foremost of these advantages are the elimination of vibration which will greatly prolong the life of the drill. Other advantages are the increased number of blows which may be delivered to the working implement within-a given period of time and the consequent greater footage of drilling that may be obtained by means of a drill thus constructed than is the case in the type of drills heretofore employed. These advantageous results may be obtained without constructing the pistons of such proportions and weight as to be detrimental to the elements against which they strike or react.

The following description of the operation of the invention will be helpful in obtaining a clearer understanding of its advantage The operation is as follows: \Vith the throttle valve Y in the open position illustratcd, pressure fluid enters the supply reservoir 0 thence flows through the ports and h into the valve chamber In. ith the valve m in the position illustrated pressure fluid flows into the passage 1, thence through the inlet passage 2) into the rearward end of the piston chamber J to impel the piston R forwardly to deliver its blow against the anvil block 5. At the same time pressure fluid will flow through the inlet passage it into the front end of the iston chamber K for impelling the piston rearwardly.

As the pistons Q, and R move in the directions described and after they have covered the exhaust ports of their respective piston chambers, the air in the ends of the piston chambers towards which the pistons are moving will be compressed and such compression will flow through the inlet passages w and t to act against the valve :0 for throwing it to its other limiting position.

When the piston R is about to deliver its blow and the piston Q. reaches the rearward position in the piston chamber K, the exhaust ports G and P will be uncovered. This will permit the pressure fluid used for actuating the pistons to escape to the atmosphere and will therefore cause an abrupt drop in pressure in the passage 1". The compression in the passage 8 then having reached its maximum degree together with such pressure fluid as may flow through the ports 72 to act against the valve will throw the valve 00 against the plug 0 to cut off the admission of pressure fluid into the passage 1 i lVith the valve a reversed in the manner described the passage of s will be uncovered. Pressure fluid will then flow from the valve chamber through the passages s and t into the rearward end of the piston chamber K to drive the piston Q forwardly against the anvil block S. Likewise pressure fluid will flow from the passage 8 through the inlet passage to into the front end of the piston chamber J to act against the piston R for impelling it rearwardly. After the pistons Q, and R have moved to a point where they will cover the exhaust ports P and G respectively, the air in the front of the pistons will be compressed and will flow through the inlet passages v and a into the passage 1 to act against the seated end of the valve 00 to again reverse it to its initial position, thus completing the cycle of operations.

I claim 1. A rocl-r drill, comprising an outer cylinder having a wall forming a piston chamber, an inner cylinder having a wall extending into the outer cylinder forming a piston chamber, a projection on one end of the inner cylinder extending into the outer cylinder for centralizing the cylinders with respect to each other, said reciprocatory hammer piston chambers having exhaust ports, pistons in the piston chambers controlling the exhaust ports, an anvil block slidably guided by the outer cylinder and associated with the piston chambers for transmitting the blows of the piston to an element intended to be actuated, valve means for effecting the distribution of pressure fluid to the piston chambers, and ports and passages in the walls of the cylinders leading from the valve means to the piston chambers for conveying pressure fluid thereto to simultaneously actuate the pistons in opposite directions with respect to each other.

2. A rock drill, comprising an inner cylinder having a wall forming a piston chamber, an outer cylinder spaced with respect to the inner cylinder and having a wall forming an annular piston chamber, ports and passages in the walls of the inner and outer cylinders for the admission and exhaust of pressure fluid to and from the piston chambers, and hammer pistons in the piston chambers actuated by the pressure fluid for delivering alternate blows to a working implement.

3. A rock drill, comprising an inner cylinder having a Wall forming a piston chamber, an outer cylinder spaced with respect to the inner cylinder and having a Wall forming an annular piston chamber, inlet passages extending longitudinally along the walls of the inner and outer cylinders to admit pressure fluid to one end of the piston chambers, exhaust ports in the walls or" the inner and outer cylinders to exhaust pressure fluid from said piston chambers, hammer pistons in the piston chambers actuated by the pressure fluid for delivering alternate blows to a working imspecification.

JAMES F. SHOOK.

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